I'am coming to china by the end of this month to study electrical information engineering in yunnan university .i was wondering is college hard in china ? How many hours do students study per day in chinese universities ?

Are you studying for a degree or are you studying for some other college certificate?
Chinese universities generally have a reputation for being easy, with some students only turning up half the time, if that. However, I also know that engineering degrees are sought after and getting a place on a degree course can be highly competitive. That implies that courses attract some of the top students, who are highly motivated and demands may be high.

If you are doing a non degree course, some of the students will not be motivated, and probably failed the Gao Kao exams (needed for uni entrance) in high school.

In short no simple answer, sorry.

you can sleep your way through it if you want. they don't fail anybody. they still haven't addressed this issue/loophole.

They don't fail anyone anywhere anymore. To be fair, they hardly ever did - even back in the 1970s when I was at university, unless you call a third a fail.

My own personal expulsion with several peers at the collegiate level, albeit anecdotal, refutes your overgeneralizing claim!

In china I can't say for sure if college is easier then abroad. I know in Canada and the Usa (not all schools) it works like this if your GPA falls below 2.5 (roughly 60% average) you are on probation for a semester if you fall below 2.0 (50%) you are failed out of your program. now more competitive programs (law, Medicine, Engineering, and computer sci) have higher minimums. in china as a foreigner paying more then average chinese citizens and being good for a school you likely wont fail regardless of your work

It is worth pointing out that getting into, and graduating from postgrad in mainland China is a totally different ball game to undergrad study. As it is in most countries.
I have been told by a Chinese University's Dean that post grad is much more rigorous. She was bemoaning the fact that undergrad students today do not want to work, and don't work as hard as they had to 30 years ago; a generalization on her part. She complained that they still had to pass undergraduate students, as a failure is not acceptable. However, the professors had been allowed to maintain standards in post graduate courses.

Strange that holding students to a certain standard isn't really an expectation in undergrad. Definitely wasn't my experience when I studied (which was a long time ago, granted). It seems like degrees in general have been watered down over the last 20-30 years. It's a shame.